Coupled continuum modeling of size-segregation driven by shear-strain-rate gradients and flow in dense, bidisperse granular media

Abstract

Dense granular systems that consist of particles of disparate sizes segregate based on size during flow, resulting in complex, coupled segregation and flow patterns. The ability to predict how granular mixtures segregate is important in the design of industrial processes and the understanding of geophysical phenomena. The two primary drivers of size-segregation are pressure gradients and shear-strain-rate gradients. In this work, we isolate size-segregation driven by shear-strain-rate gradients by studying two dense granular flow geometries with constant pressure fields: gravity-driven flow down a long vertical chute with rough parallel walls and annular shear flow with rough inner and outer walls. We perform discrete element method (DEM) simulations of dense flow of bidisperse granular systems in both flow geometries, while varying system parameters, such as the flow rate, flow configuration size, fraction of large/small grains, and grain-size ratio, and use DEM data to inform continuum constitutive equations for the relative flux of large and small particles. When the resulting continuum model for the dynamics of size-segregation is coupled with the nonlocal granular fluidity model (a nonlocal continuum model for dense granular flow rheology), we show that both flow fields and segregation dynamics may be simultaneously captured using this coupled, continuum system of equations.

arXiv comment29 pages with 14 figures

References in corpus (13)

• On dense granular flows
• Rheophysics of dense granular materials : Discrete simulation of plane shear flows
• Crucial role of side walls for granular surface flows: consequences for the rheology
• Creep motion in a granular pile exhibiting steady surface flow
• Self-diffusion in dense granular shear flows
• Annular shear of cohesionless granular materials: from inertial to quasistatic regime
• Modeling size segregation of granular materials: the roles of segregation, advection and diffusion
• A Microscopic Description of the Granular Fluidity Field in Nonlocal Flow Modeling
• Power-law scaling in granular rheology across flow geometries
• From discrete elements to continuum fields: Extension to bidisperse systems
• Modelling segregation of flowing bidisperse granular mixtures varying simultaneously in size and density
• Viscometric flow of dense granular materials under controlled pressure and shear stress
• Self-Diffusion Scalings in Dense Granular Flows

Cited by in corpus (4)

• General model for segregation forces in flowing granular mixtures
• Continuum modeling of size-segregation and flow in dense, bidisperse granular media: Accounting for segregation driven by both pressure gradients and shear-strain-rate gradients
• Transient segregation of different density granular mixtures
• Granular segregation across flow geometries: a closure model for the particle segregation velocity